Organoxysilyl or siloxy-containing ethylnorbornene compounds are very useful for filler addition and siloxane modification which are typical means for improving physical properties of polymers, especially metathesis polymerization polymers (see JP-A 2009-255380 and JP-A 2005-097265).
One known method for preparing organoxysilyl or siloxy-containing ethylnorbornene compounds is hydrosilylation of 5-vinyl-2-norbornene with a hydrogen organoxysilane or siloxy compound (WO 2008/082128). However, the prior art hydrosilylation methods including the method of WO 2008/082128 have poor reactivity and exhibit low selectivity of the target product because a substantial amount of adduct is formed by addition to the endocyclic double bond of norbornene ring. Moreover, since the adduct formed by addition to the endocyclic double bond and the target product have the same molecular weight and hence approximate boiling points, it is difficult to separate them via distillation, leading to reductions of both purity and yield. Formation of a bissilyl adduct by addition to both the double bonds further reduces the yield of the target product.
When hydrosilylation reaction of 5-vinyl-2-norbornene with trimethoxysilane is conducted in the presence of a chloroplatinic acid catalyst, for example, there arises a problem that not only the target product, i.e., 5-(2-trimethoxysilylethyl)-2-norbornene (a) is obtained, but also vinylnorbornyltrimethoxysilane (b) by addition to the endocyclic double bond and bissilyl adduct (c) by addition to both the double bonds form in noticeable amounts.

It is necessary to selectively obtain an organoxysilyl or organoxysiloxy-containing ethylnorbornene compound with high purity. If a norbornene compound with low purity is used as a monomer for polymerization, physical properties (specifically, mechanical, thermal, and optical) of the resulting polymer may be reduced or altered. If a vinyl compound is incidentally available during ring-opening metathesis polymerization of norbornene compounds, the vinyl compound may act to stop the ring-opening metathesis polymerization and interfere with molecular weight control. Accordingly, it is desirable to have a method for effectively preparing an organoxysilyl or siloxy-containing ethylnorbornene compound at high purity and selectivity.